1. Technical Field
The present invention relates to a technical field of an electro-optical device, such as a liquid crystal device, and an electronic apparatus, such as a liquid crystal projector, provided with the electro-optical device.
2. Related Art
In an electro-optical device of this type, data lines and scanning lines are wired on a substrate so as to intersect with each other, pixel electrodes are provided in a matrix at positions corresponding to intersections of both the data lines and the scanning lines, and the pixel electrodes are controlled for switching pixel by pixel. Each pixel provides a thin film transistor (TFT) having, for example, a lightly doped drain (LDD) structure as a pixel switching element that controls switching of the pixel electrode.
On the other hand, a liquid crystal device, which is an example of the above electro-optical device, is not only used for a direct-view-type display but also used widely, for example, as a light modulating device (light valve) of a projection-type display device. Particularly, when in a projection-type display device, because intensive light emitted from a light source enters a liquid crystal light valve, a light shielding film, which serves as a light shielding device that blocks incident light, is installed in the liquid crystal light valve so that a TFT in the liquid crystal light valve does not cause an increase in leakage current and/or a malfunction, or the like, because of the intensive light.
In regard to the above light shielding device or the light shielding film, Japanese Patent No. 3731447 and JP-A-2004-4722 describe a technology for shielding a channel region in such a manner that the width of a gate electrode is formed to be wider than the width of a semiconductor layer of a transistor as viewed in plan. In addition, JP-A-2005-45017, Japanese Patent No. 3307144, JP-A-2000-356787, JP-A-2004-170656, and JP-A-2006-171136 describe that contact holes or dummy contact holes that simply shield a semiconductor layer against light are formed on both sides of the semiconductor layer, and light that travels from the sides of the semiconductor layer is blocked by light shielding films deposited in the contact holes or dummy contact holes. The above light shielding films are, for example, integrally formed with the same conductive film of the gate electrode or, according to JP-A-2003-307725, the light shielding film is provided in a layer that is separate from the gate electrode.
Here, when the TFT having an LDD structure is provided as a pixel switching element, in the semiconductor layer of the TFT, particularly, light leakage current tends to easily occur in an LDD region on a side that is electrically connected to the pixel electrode in comparison with an LDD region on a side that is electrically connected to the data line. The above described Japanese Patent No. 3731447, JP-A-2004-4722, JP-A-2005-45017, Japanese Patent No. 3307144, JP-A-2000-356787, JP-A-2004-170656, and JP-A-2006-171136 do not specifically describe light shielding for the above LDD regions and, therefore, there is a possibility that light leakage current may occur in the TFT because of entry of light into the LDD region on a side that is electrically connected to the pixel electrode. Because of the above light leakage current in the TFT, there has been a technical problem in which display defects, such as flicker or pixel chrominance nonuniformity, may occur and, as a result, the quality of a display image decreases. In addition, the light shielding structure of JP-A-2003-307725 has a large area in which a light shielding film is arranged in each pixel and a complex configuration such that various films including the light shielding film are laminated in multiple layers. Thus, there is a technical problem that the manufacturing process thereof may be further complicated.